A vane rotary compressor is used for an air conditioner or the like and compresses a fluid such as refrigerant to supply the compressed fluid to the outside.
FIG. 1 is a cross-sectional view schematically illustrating a conventional vane rotary compressor disclosed in Japanese Patent Laid-open Publication No. 2010-31759. FIG. 2 is a cross-sectional view taken along line “A-A” in FIG. 1.
As illustrated in FIG. 1, the conventional vane rotary compressor, which is designated by reference numeral 10, includes a housing H configured of a rear housing 11 and a front housing 12 while defining an external appearance thereof, and a cylindrical cylinder 13 received within the rear housing 11.
In this case, the cylinder 13 has an inner peripheral surface having an oval sectional shape as illustrated in FIG. 2.
In the inside of the rear housing 11, a front cover 14 is coupled to the front of the cylinder 13 and a rear cover 15 is coupled to the rear of the cylinder 13. In addition, a discharge space Da is defined between an outer peripheral surface of the cylinder 13, an inner peripheral surface of the rear housing 11 facing the same, the front cover 14, and the rear cover 15.
A rotary shaft 17 passing through the cylinder 13 is rotatably installed to the front cover 14 and the rear cover 15. The rotary shaft 17 is coupled with a cylindrical rotor 18, and the rotor 18 rotates within the cylinder 13 along with the rotary shaft 17 when the rotary shaft 17 rotates.
As illustrated in FIG. 2, a plurality of slots 18a is radially formed on an outer peripheral surface of the rotor 18, a linear vane 20 is slidably received in each of the slots 18a, and lubricant oil is supplied into the slot 18a. 
When the rotor 18 is rotated by the rotation of the rotary shaft 17, a tip portion of the vane 20 protrudes outward of the slot 18a and comes into close contact with the inner peripheral surface of the cylinder 13. In this case, a plurality of divided compression chambers 21 is provided, each being formed by the outer peripheral surface of the rotor 18, the inner peripheral surface of the cylinder 13, a pair of vanes 20 adjacent to each other, and a facing surface 14a of the front cover 14 and a facing surface 15a of the rear cover 15, which face the cylinder 13.
In the case of the vane rotary compressor, an intake stoke is a stroke in which the volume of the compression chamber 21 is increased whereas a compression stroke is a stroke in which the volume of the compression chamber 21 is decreased, according to the rotation direction of the rotor 18.
As illustrated in FIG. 1, the front housing 12 has a suction port 24 formed at an upper portion thereof, and a suction space Sa communicating with the suction port 24 is defined within the front housing 12.
The front cover 14 has an inlet 14b communicating with the suction space Sa, and a suction passage 13b communicating with the inlet 14b is formed to axially pass through the cylinder 13.
As illustrated in FIG. 2, discharge chambers 13d recessed inwards are provided at opposite sides of the outer peripheral surface of the cylinder 13. In this case, the pair of discharge chambers 13d communicates with the compression chambers 21 through associated discharge holes 13a, and forms a portion of the discharge space Da.
The rear housing 11 is provided with a high-pressure chamber 30 divided by the rear cover 15 so that a compressed refrigerant is introduced into the high-pressure chamber 30. That is, the inside of the rear housing 11 is divided into the discharge space Da and the high-pressure chamber 30 by the rear cover 15. In this case, any one of the pair of discharge chambers 13d is formed with an outlet 15e communicating with the high-pressure chamber 30.
Accordingly, when the rotor 18 and the vanes 20 rotate along with the rotation of the rotary shaft 17, a refrigerant is introduced from the suction space Sa via the inlet 14b and the suction passage 13b to each compression chamber 21. The refrigerant compressed by a reduction in volume of the compression chamber 21 is discharged to the discharge chamber 13d through the associated discharge hole 13a to be introduced into the high-pressure chamber 30 through the outlet 15e, and is then supplied to the outside through a discharge port 31.
Meanwhile, the high-pressure chamber 30 is provided with an oil separator 40 for separating lubricant oil from the compressed refrigerant introduced into the high-pressure chamber 30. An oil separation pipe 43 is installed at an upper portion of a case 41, and an oil separation chamber 42 into which the separated oil is dropped is formed beneath the oil separation pipe 43. Thus, the oil in the oil separation chamber 42 flows down into an oil storage chamber 32, which is formed in a lower portion of the high-pressure chamber 30, through an oil passage 41b. 
The oil stored in the oil storage chamber 32 lubricates a sliding surface between the rear cover 15 and rotor 18 via a lubricant space of a bush, which supports a rear end of the rotary shaft 17, through an oil supply passage 15d. Subsequently, the oil is reintroduced into the outlet 15e through an oil return groove 45 by a difference in pressure between the discharge space Da and the high-pressure chamber 30.
However, since the vane 20 protrudes outward of the rotor 18 along the slot 18a in a case in which the linear vane 20 is applied to the conventional vane rotary compressor 10, hitting noise is caused while the tip portion of the vane 20 strikes the inner peripheral surface of the cylinder 13.
FIG. 3 is a cross-sectional view schematically illustrating a curved blade type vane rotary compressor disclosed in Japanese Patent Laid-open Publication No. 2002-130169.
The vane rotary compressor shown in FIG. 3 includes a cylindrical cylinder 1, a rotor 2, and a drive shaft 3. In this case, the cylinder 1 includes an inlet 1A and an outlet 1B and the rotor 2 is eccentrically installed within the cylinder 1.
A plurality of curved blade type vanes 4 is provided on an outer peripheral surface of the rotor 2 so that a plurality of divided compression chambers 6 is formed between the cylinder 1 and the rotor 2. One side of each of the vanes 4 is hinge-coupled to the outer peripheral surface of the rotor 2 by an associated hinge pin 5.
While the rotor 2 rotates by a predetermined angle from a time at which a compression stroke ends when the vane 4 passes through the outlet 1B to a time at which an intake stroke begins when the vane 4 passes through the inlet 1A, a back portion of the vane 4 is pressed toward rotor 2 by an inner peripheral surface of the cylinder 1 as illustrated in an enlarged view of FIG. 3. In this case, a tip portion of the vane 4 is spaced apart from the inner peripheral surface of the cylinder 1.
Subsequently, when the force applied to the back portion of the vane 4 is instantaneously removed as a gap between the outer peripheral surface of the rotor 2 and the inner peripheral surface of the cylinder 1 is increased by rotation of the rotor 2, the tip portion of the vane 4 comes into contact with the inner peripheral surface of the cylinder 1 while the vane 4 pivots and is unfolded from the rotor 2.
In this case, when the vane 4 folded by the rotor 2 is unfolded toward the inner peripheral surface of the cylinder 1 due to an increase in rotational moment of inertia of the vane 4 when the rotor 2 rotates at high speed, hitting noise is caused while the tip portion of the vane 4 strikes the inner peripheral surface of the cylinder 1.
In addition, the back portion of the vane 4 comes into contact with the inner peripheral surface of the cylinder 1 at the initial stage of the intake stroke and the vane 4 is rapidly unfolded from the rotor 2 after the intake stroke somewhat proceeds, so that the tip portion of the vane 4 is supported by the inner peripheral surface of the cylinder 1. Therefore, the volume of the compression chamber 6 is not smoothly expanded, resulting in a reduction of suction flow rate.
Meanwhile, since a center of gravity of the vane 4 is formed in the vicinity of the hinge coupling portion between the vane 4 and the rotor 2 in the conventional curved blade type vane 4, the vane 4 has a small rotational moment when the rotor 2 rotates.
For this reason, an internal leak is generated by a delay of a rotation operation time until the vane 4 is unfolded from the rotor 2 and the tip portion of the vane 4 comes into contact with the inner peripheral surface of the cylinder 1. The internal leak causes a reduction of compression flow rate of the refrigerant.
The above description is will be given in more detail with reference to FIG. 4.
FIG. 4 is a view schematically illustrating forces acting on the curved blade type vane 4 when the rotor 2 rotates.
In the vane rotary compressor illustrated in FIG. 3, the vane 4 is unfolded from the rotor 2 when the rotor 2 rotates and the tip portion of the vane 4 comes into close contact with the inner peripheral surface of the cylinder 1, thereby forming the compression chamber 6.
The forces applied to the vane 4 will be described according to action directions thereof with reference to FIGS. 3 and 4. A centrifugal force A1 according to rotation of the rotor 2 and a rotational moment A2 according to a center of gravity of the vane 4 act as forces of pushing and rotating the tip portion of the vane 4 toward the inner peripheral surface of the cylinder 1.
On the contrary, a hinge friction force B1 of the vane 4, a rotational moment of inertia B2, a fluid resistance B3 of a refrigerant in the compression chamber 6, a friction force B4 between the vane 4 and the cylinder 1, and a viscosity B5 of lubricant oil act as forces of pulling the tip portion of the vane 4 toward the outer peripheral surface of the rotor 2.
In this case, when the forces B1 to B5 of pulling the tip portion of the vane 4 toward the outer peripheral surface of the rotor 2 are larger than the forces A1 and A2 of pushing the tip portion of the vane 4 toward the inner peripheral surface of the cylinder 1, a gap is formed between the vane 4 and the cylinder 1 as illustrated in FIG. 4.
In this case, the compression chamber 6 is not fully sealed by the vane 4 and an internal leak is generated between the compression chamber 6 and the adjacent compression chamber 6, thereby causing a reduction of compression flow rate of the refrigerant.
In addition, the gap between the vane 4 and the cylinder 1 is gradually increased during a delay of rotation operation of the vane 4. Accordingly, there is a problem in that hitting noise is caused when the tip portion of the vane 4 instantaneously comes into contact with the inner peripheral surface of the cylinder 1 due to the centrifugal force A1 according to rotation of the rotor 2 and the rotational moment A2 of the vane 4.
In addition, in the conventional vane rotary compressor, the tip portion of the vane 4 has a rounded arc shape. The tip portion of the vane 4 is rubbed against the inner peripheral surface of the cylinder 1 when the rotor 2 rotates, and thus a contact shifting distance shifted along the tip portion of the vane 4 is very short. As a result, friction characteristics similar to sliding friction are exhibited in the vane 4 on the inner peripheral surface of the cylinder 1.
Wear between the tip portion of the vane 4 and the inner peripheral surface of the cylinder 1 is increased as friction is locally generated due to the above friction characteristics, and durability of the compressor is deteriorated by generation of noise and internal leak when the compressor is driven for a long time due to the above friction characteristics.